<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>圆角</title>
<style type="text/css">
div {
	width: 800px;
	height: 300px;
	border: 5px solid deeppink;
	margin: 0 auto;
	border-radius:200px/100px 0;
}
</style>
</head>
<body>
<div></div>
</body>
</html>